The present invention is directed to a safety apparatus for a pneumatic bed, which prevents the bed from being raised or inflated beyond a certain level. More particularly, the present invention relates to a pneumatic mat type bed designed for double-folding, i.e. raising an upper portion thereof with respect to a lower portion thereof so that an individual on the bed can sit up. The bed is provided with a plurality of small-size pneumatic mats, with gas such as air either fed to or exhausted from the respective mats to inflate or delfate the same, e.g. through control by a computer. An inflatable member such as an air bag is installed on the upper section or half of the bed, to raise the same, with the safety mechanism being provided to prevent the upper part of the bed from raising or springing up more than a predetermined extent, due to any failure of the computer or other mechanisms to arrest the flow of gas or air into the air bag.
The present invention is also directed to a plurality of pneumatic mats for a pneumatic type bed, with each individual pneumatic mat being provided with such a safety apparatus. An electromagnetic valve is provided through which gas such as air is fed to or exhausted from the respective pneumatic mat, e.g. through control by a computer.
A prior pneumatic mat-type bed has been formed by a plurality of pneumatic mats, allowing a user who is incapacitated or who can move only with great difficulty, to raise individual parts of his body, e.g. his legs, head, left or right body half, or his back, by himself or with the aid of a helper. The bed can be so raised through the operation of a computer by the user, or the user's helper, in order to protect the user from various ailments by being bedridden, e.g. bed sores or poor blood circulation.
Recently, a pneumatic mat-type bed designed for double-folding has been developed, wherein the upper half of the bed is raised or springs up by inflation of an air bag.
A prior pneumatic mat-type bed has also been constituted by several small size pneumatic mats, each formed as a bellows between an upper plate thereof and a bottom plate thereof, with gas such as air being fed to or exhausted from the bellows through a pipe and a gas feeding/exhaust valve, under the control of a computer.
The problem of these previously-used beds, is that the air or gas bag may spring up to an undesired extent due to misoperation of or a fault in the controlling mechanism for inflating the bag, which would extremely discomfort the user, e.g. a patient. At the worst, the gas bag could explode. By the same token, a problem with the prior art pneumatic-type beds utilizing the individual mats or bellows-type members, is that if gas feeding is not arrested due to some possible malfunctioning of the computer, then a user e.g. a patient) of the bed having the pneumatic mats may be thrown off or dropped off the bed, or the pneumatic mats might even explode. Thus, there is a need for provision of some safety means or mechanism to prevent these accidents from occurring, especially to a patient who is an invalid, i.e. cannot move by himself.